1. Field of the Invention
The objective of the invention is a plaster which at the same time is a dosing device.
2. Description of the Prior Art
Different plasters are known. The simplest form of a plaster is a strip to be adhered onto the wound or other spot of treatment. The plaster can also be furnished with a gauze dressing, which can be filled (impregnated) with some suitable substance. By this a simple means is achieved for local (topical) treatment of an injury or simply for protection from external contamination.
In recent years, plasters applied with drugs and dosage devices have become all the more important in the administration of integrated active drugs. The integrated (systemic) dosing devices can be divided into two main groups. In the first group, the drug composition is contained in the adhesive or is impregnated into a suitable porous substance (membrane), which adhered to the skin starts delivering the active ingredient.
The other group comprises dosing devices, which usually contain a reservoir having a membrane as one wall through which the substance to be dosed is administered to the skin.
The above mentioned means are below presented illustrated by their patent publications.
Plasters, in which the drug is contained in the adhesive, or the drug is in a reservoir, which all over is covered by adhesive, or in which the drug is solved, or is contained in a fungous material through which it can be freely delivered, and in which the adhesive surrounds the contact layer between the reservoir and the patient but does not cover the contact surface, are described in the U.S. Pat. Nos. 3,598,122, 3,589,123, 3,731,683, 3,734,097, 3,742,951 and 3,797,494.
The FI applications 870 557 and 865 088 present a dermal or transdermal dosing system, in which beneath a substance impermeable top layer is a drug reservoir and a membrane, the surface of which facing the skin is adhered to the skin, leaving part of the membrane free for the dosing. The membrane is moreover surrounded by an adhesive slip, and the active ingredient is stored beneath the top layer. The WO 90/07328 publication presents an application device, in which the active ingredient is placed in a ring-shaped opening (chamber) inside the periphery underneath the top layer. In this model the top layer or part of it can be opened and closed and moreover the chamber can contain a membrane.
The WO 93/00955 publication presents a dosing device, having a separate bellows-like gear in the drug reservoir, which at increased temperature delivers the substance to be dosed through the membrane and performs the dosing through the wall formed of the chamber membrane.
In the CH 560 544 publication is presented a dosing device similar to the one described above, in which the active ingredient is in a reservoir having a membrane as one wall. The means can also contain a second chamber, the increase in volume of which leads to a decrease in the reservoir, and thus to an increased dosing. The ingredient to be administered can be added to the reservoir. The bandage is adhered to the skin from its edges 2 containing the adhesive agent.
The U.S. Pat. No. 4,224,941 publication presents a pressurized application device for skin treatment. The device is at rest folded and has under pressure a ball-shaped part. This hyberbaric device is used for treatment of a desired spot at a certain pressure.
The storage of some of the devices described above cause problems. The active ingredient of some of the devices is stored inside the membrane, by which it might concentrate in some part of the membrane. Some devices have to be stored in a certain position. The membrane of some devices might in use come off the skin, and the adhesive area of some adhered membranes reduces the treatment area. The use of some active ingredients restricts the amount of adhesives. Some devices requires filling of the active ingredient after the attachment. The adhesion-drug contact of some devices is continuous. The dosage of some of the devices described above resembles oral administration illustrated by the time-dose diagram and cannot be changed. Some devices are not suitable for home treatment.